Ordering parts to go along with stump jumper.

[Half-a-Day Farm]

Ok, thanks to the good advice I found on this site I managed to remove the bent stump jumper from my 2000 Challenger MC606 cutter. This came with the 2000 Challenger MT265 tractor I bought. I have never used a cutter before and when I tried it out it wobbled the whole tractor. So I stopped. I flipped it on it's side, sprayed it with penetrating oil, removed the nut, pounded wedges in between the stump jumper and reinforcing bar, put the nut back on backwards and wacked it with a sledge. Boom. It popped off.

The PTO shaft telescopes freely and the blades have got a few wallops but not too bad. The gearbox spins smoothly and I see no leaks. I'm presuming the vibration stems from the bent stump jumper. (If I put this thing in a press I could probably straighten it out (somewhat)). Not sure if that's a good idea.

With the stump jumper off, looking from the bottom of the cutter it looked like at first a rusty washer partly rotted/missing and underneath that feels like rubber. The questions I have are: how do I correctly measure the spline so I order the right stump jumper? While I'm at it I'll probably order new blades too. And what do I do about this thing I'm not sure is a washer? I'm guessing it protects the rubber seal and bearings.

Suggestions and advice cheerfully accepted!